The US Missile Defence Agency (MDA) has announced a failed test of its controversial Groundbased Midcourse Defence interceptor. The agency blamed the test failure on problems with the Sea Based X-Band radar, well known for its resemblance to an enormous golfball mounted on an oil rig.
Reassuringly expensive.
In a brief …

COMMENTS

X-Band radar?

So the new state of the art missile defense system is reliant on 1970's style radar gun technology? Most police departments in the US have stopped using the X-Band due to interference form microwave ovens, commercial motion sensors and wildly available (albeit illegal) radar jamming devices you can pick up at any Ham radio swap meet. I find it kinda troublesome that we are basing the so called missile shield technology on such antiquated radar systems that could be so easily jammed with a few parts from old microwave, radar gun and radio shack...

Mines the one with the circa 1960 plans for the backyard bomb shelter in it...

X-Band

Is in the range 8-10 GHz, and can also be called I-Band under the new designation system, it has nothing to do with how the signal is generated or used. I'd imagine they aren't just using a really big police speed camera to track a warhead outside the Earth's atmosphere at high Mach, if there's a source of interference it'll be this thing.

Less powerful X-Band fire control radars are more than capable of cooking someone who stands in front of it when it's turned on. I/X-band is also used in navigation and weather radars, basically due to a combination of the accuracy you can achieve and the range you can achieve it at, which is mostly down to the frequency. Of course a speed camera is probably just using a CW signal to asses the Doppler shift, the fire control radar will be doing all kinds of tricks to get an accurate position course and speed, including Pulsed-CW, Mono-pulse tracking and other stuff that hurts to think about.

Microwave ovens are on 2.45GHz (S-Band) and X-band is around 10GHz (although the band is quite wide and it depends on which country you are in and which service you are allocated to--assume X-Band extremities between 8-12GHz).

Here's a bandplan list from Wiki (but get accurate info from the ITU):

L band 1 to 2 GHz

S band 2 to 4 GHz

C band 4 to 8 GHz

X band 8 to 12 GHz

Ku band 12 to 18 GHz

K band 18 to 26.5 GHz

Ka band 26.5 to 40 GHz

Q band 30 to 50 GHz

U band 40 to 60 GHz

V band 50 to 75 GHz

E band 60 to 90 GHz

W band 75 to 110 GHz

F band 90 to 140 GHz

D band 110 to 170 GHz

It's possible that harmonics from μWave ovens will interfere with X-Band and they sometimes do but there's a lot of other activity on X-Band including intruder alarms and such that cause interference. Also, there are other technical reasons why the coppers have moved mostly elsewhere.

The reason why X-Band was and still is used has to do more with the propagation characteristics of those frequencies than interference. For certain applications, X-band provides a good compromise between atmospheric penetration (absorption), range and object resolution.

In WW-II, X-Band was the Allies' pièce de résistance--the secret king hit that gave them the competitive edge in RADAR. However, being old is irrelevant, it's applicability to the application that matters, and X-Band works just as well on flying objects now as it did back then.

Loos like one ....

So critics of system are still critical.

Ho hum. Well theyv'e only been at it for the better part of 6 decades. They are getting better.

If only the opposition was not getting better as well. It would be particulalrly interesting if the radar was working OK. That would mean it was not as good at winnowing out the decoys from the (theoretically) live warheads.

Decoys work. Who'd have thought it?

It's quite sad that some of the amazing solid fuel engine tech developed for previous programmes never seemed to make it into the mainstream. A burn rate of 50 inches of propellant grain/second would have been *very* impressive. From several kilometres away of course.

Given the alltitude range these these operate over some kind of altitude compensating nozzle might be a reasonable piece of tech as well.

I do Diplomacy.

Close, but no Cigar... keep on tweeking!

"improved advanced tracking of weapons coming in across the Pacific - as they would if fired from North Korea, for example, though that nation has yet to conduct a successful test of a missile capable of reaching the continental USA"

Fortunately, a single or couple missiles from North Korea have multipe chances to be hit.

"but hit a countermeasure rather than the actual target."

Hey, this is pretty good! This is a remarkable achievement, considering opponents said this would be impossible just a decade ago. This is indicative of tweeking that is needed, rather than revamping.

It is expected that every phase will not work 100% correctly 100% of the time, which is why there are multiple technologies attacking multiple phases of a missile attack in order to conduct missile kills.

- sea based countermeasures

- air based countermeasures

- ground based countermeasures

- ascent phase kills

- mid phase kills

- descent phase kills

Multiple technologies targeting different phases in a missile defense shield, provides protection where each strategy picks up from where the other leaves off... providing citizens an effective counter measure to threats from belligerent nations.

If a counter measure is successful some of the times, lives and infrastructure would be saved, which is better than the only defense nations have today against an aggressor threatening action - full fledge pre-emptive war.

When a friendly nation has been compromised by belligerent unlawful combatants (i.e. terrorists), there is not even a countermeasure today.

@ A.C. "X-Band radar?" - BTW, I forgot to mention the bit on Jamming.

@ A.C. "X-Band radar?" - BTW, I forgot to mention the bit on Jamming.

ANY microwave frequency* that's useful for tracking planes, rockets or similar has the potential for being jammed. And potential jamming devices, irrespective of the frequency, are easily available and comparatively cheap.

However, military RADAR is not easily jammed. In fact, it requires considerable effort and expertise--that of the level expected of a military opponent to jam it. Electronic warfare is now very sophisticated and small low power stuff will have little or no effect. There are many reasons for this, a few include very high power (produces good signal-to-noise ratio), directivity--you have to be in the line of detection which can be very narrow and highly directive with those huge golf ball-type microwave lenses, and specialised signal processing (in which special and often secret algorithms can separate crap and interference from the wanted signal).

Military radar is now extremely sophisticated and the least of its worries are people toying around with Tandy bits or surplus ex-WW-II disposals equipment.

___

* Some microwave frequencies are just not suitable for tracking flying objects, especially wavelengths at the edges of the microwave spectrum, or those where atmospheric absorption (water vapour) or excessive scatting are problems; and some wavelengths are just not suited to providing the appropriate resolution for this type of work.

@AC

AC, we have electromagnetic radiation to play with. Radio propogates well thru the atmosphere, light does not. We haven't yet mastered gravity, though my neighbour assures me she is doing repeated cyclical work on the matter.

Thus to call radar old tech is rather silly. It's the only tech we have.

I'm sure I've heard this story before

@Graham WIlson

"There are many reasons for this, a few include very high power (produces good signal-to-noise ratio), directivity--you have to be in the line of detection which can be very narrow and highly directive with those huge golf ball-type microwave lenses, and specialised signal processing (in which special and often secret algorithms can separate crap and interference from the wanted signal"

I think the point is that this radar probably had *all* this installed. It *still* couldn't sort the warhead from the chaff. On the radar front I guess this depends on weather this is a mature more-or-less off the shelf miltary radar or a highly experimental brassboard loaded with a bunch of new v0.9 detection algorithms. Being ground based it would not matter too much if the signal processing took up several racks and ate kilowatts as long as they *worked*.

In fact it's not clear if the test vehicle was using *any* kind of active jamming. If it wasn't this make the test even less impressive.